P1241 括号序列

#include<iostream>
#include<stack>
using namespace std;

const int N = 110;

stack<int> pos;
char s[N];
int st[N];

int main(){
    
    cin >> s + 1;
    
    for(int i = 1; s[i]; i ++)
        if(s[i] == '[' || s[i] == '(') pos.push(i);
        else if(pos.size()){
            int j = pos.top();
            if(s[j] == '[' && s[i] == ']' || s[j] == '(' && s[i] == ')'){
                st[j] = st[i] = 1;
                pos.pop();
            }
        }
    
    for(int i = 1; s[i]; i ++){
        if(st[i]) cout << s[i];
        else{
            if(s[i] == '[' || s[i] == ']') cout << "[]";
            else cout << "()";
        }
    }
    
    return 0;
    
}